82 THE JOUllNAL OF 130TANY 



certain other nationals of late, that what to me had once been a 

 welcome guest began to take on the appearance of an undesirable 

 alien. 



Not only did R. spli<srotheca appear in some of its forms to come 

 uncomfortably near to other South and Centi-al African species of the 

 genus, but it even invaded the ranks of other genera, for having 

 occasion to examine Pterogouiella Sluhbnanni Broth, from Usambara, 

 I recognized not only (as Brotherus himself had already done) that it 

 belonged to Rhcq^hidostegium, but also that it was a large, scorpioid- 

 branching form of R. sphcerotJieca, almost identical, in fact, with my 

 original Table Mt. acquaintance. 



Having subsequently to examine R. Duisahoanum (Mont.) Jaeg., 

 from the Mascarene Is., I became at once aware that I had to do 

 with the same species, and it was therefore interesting to find 

 that Bescherelle, with his wide knowledge of continental and insular 

 forms, had recognized it as a highly variable species, and had brought 

 into its synonymy, among other things, Hypmim Rohillardii Duby, 

 which had got into so far removed a genus as Leucomhim. He 

 describes several forms and varieties of the species. 



Now I have learned that in the somewhat rare cases when a 

 species of moss has a fairly wide distribution in Southern and Central 

 Africa, and in Madagascar and the East African Islands, and more 

 especially when it is a plastic species, it is desirable to look further 

 afield, and see if it be not identical with some well-known species of 

 South America, or of Australasia, or both — Dicranoloma Billardieri^ 

 Ditrichum flexifolium, and Campyl.o'pu& introjiexns are cases in 

 point. Bescherelle (Fl. Bryol. Keunion, IGO) indicates the clue 

 when he writes, of It. Duisahoanum : — " Le lih. Duisahoanum, de 

 meme que le Rh. cesjyifosum des Antilles, varie beaucoup comme port, 

 comme couleur et comme disposition des f euilles ; cette difference 

 tient sans doute a I'influence des localites ou il a ete recueilli, car on 

 ne rencontre dans les diverses varietes enumerees ci-apres aucun carac- 

 tere assez saillant pour constituer une espece speciale." 



The possibility of the identit}^ of the two, however, had not, it 

 appears, occurred to him. M}^ object in this paper is to establish the 

 identity, not only of these two, but of several other described species 

 from various parts of the workl. 



The South American and West Indian plants of this group have 

 been described under the principal headings of Hj/pnum coespitosum 

 Sw., from the West Indies ; Hypnum loxense Hook, from Peru ; H. 

 lithophilum Hornsch. and H. galipense C. M. from tropical South 

 America. C. Mueller by the time of the publication of the Synopsis had 

 recognized that of these II. galip)ense was identical with //. coespitosum, 

 and H. lifJiophilum not more than a variety of H. loxense, so that 

 the geographical areas of the two already considerably overlapped. 

 He distinguishes H. loxense from H. coespitosum by italicized cha- 

 racters, most of which are rendered invalid \>^ the fact that he takes 

 his conception of II. coespitosum from, or at least includes in his 

 conception, Leshea coespitosa of Hedwig, Spec Muse. p. 233, t. 49. 

 This, however, is far removed from the plant of Swartz, having 

 much narrower, more acuminate leaves and bracts. I do not say it is 



